Chris Miller, PHD
The hepatitis B virus (HBV) is spread by mucosal or percutaneous exposure to blood or other body fluid from a person who has chronic or acute hepatitis B. A person whose blood is positive for the hepatitis B surface antigen (HBsAg) is potentially infectious. A person who is positive for both the HBsAg and the e antigen (HBeAg) is highly infectious.
About one-third of those infected with HBV (HBsAg-positive) have symptoms within 45 to 180 days after exposure (jaundice, yellowing of the whites of the eyes, dark urine, and itching). The other two-thirds of those infected develop only mild symptoms (frequently unrecognizable) or no symptoms after infection. The latter group, though, may develop the symptoms of liver disease later in life if they become chronic carriers.
About 5 percent of those infected with HBV become chronic carriers.
During the last 10 years, about 100 to 200 health-care workers have died annually from hepatitis B. The risk of acquiring hepatitis B from exposure to body fluid containing the HBeAg is about 30 percent. During 1985, an estimated 10,000 health-care workers became infected with HBV. The good news is that during 1994 (the most recent data available), the CDC reports that there were only about 1,000 health-care workers infected with HBV. This is a 90 percent reduction! It`s about time we got some good news about hepatitis B.
This decrease was likely due to vaccination of health-care workers, educational programs stressing safety in handling sharps, and the use of protective barriers and other infection-control procedures. The recommendations by CDC and the standard by OSHA on the prevention of bloodborne diseases have played key roles in reducing the occupational spread of hepatitis B.
CDC recommends hepatitis B vaccination of health-care workers who may have contact with blood or other potentially infectious body fluids. OSHA mandates that employers make the vaccination series available to such health-care workers at the employer`s expense.
The CDC now recommends in a draft guideline on infection control in health-care personnel that postvaccination screening for antibody to the HBV (anti-HBs) is advised for personnel at ongoing risk of blood exposure The presence of these antibodies indicates that the individual vaccinated has developed immunity to hepatitis B. Knowing that one has responded to the vaccine also aids in determining the appropriate post-exposure prophylaxis needed if a subsequent exposure occurs.
CDC also recommends that people who do not respond to the vaccination series (do not develop antibodies) or do not complete the three-shot vaccination series should be vaccinated with a second series of these inoculations. If they do not respond, no further vaccination series should be given and they should be evaluated for the presence of HBsAg. Chronic carriers usually are positive for HBsAg and will not respond to the vaccination.
Those who respond to the initial vaccination series and develop anti-HBs will lose measurable anti-HBs levels with time. About 60 percent will have zero readings within 12 years after the vaccination.
Nevertheless, CDC still indicates that booster doses are not needed. The reasoning is that people who respond to the initial vaccination series remain protected against clinical hepatitis infection, even when their anti-HBs levels become low or undetectable.
All of the CDC-recommended treatments for a person exposed to potentially infectious body fluids can be obtained by calling the CDC at (770) 488-6056.
The specific treatments of administering hepatitis B immune globulin (HBIG) and/or the hepatitis B vaccine depend upon the hepatitis B status of an exposed person and of the source person involved in the exposure. An example of one of the more common situations involves exposure of a previously vaccinated person who does not know if he or she actually responded to the vaccine (were never tested for anti-HBs). In this instance, if the source patient is tested and found HBsAg-positive, the exposed person is tested for anti-HBs and, if adequate, no treatment is recommended. If not adequate, a vaccine booster is given.
We must continue to encourage the new people entering hygiene and dentistry to participate in the hepatitis B vaccination program. We must continue to provide them with training on the spread and prevention of hepatitis B in the workplace and elsewhere.
Chris Miller is director of Infection Control Research and Services and professor of oral biology at Indiana University.